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Diffstat (limited to 'Documentation/EDID/HOWTO.txt')
| -rw-r--r-- | Documentation/EDID/HOWTO.txt | 39 |
1 files changed, 29 insertions, 10 deletions
diff --git a/Documentation/EDID/HOWTO.txt b/Documentation/EDID/HOWTO.txt index 75a9f2a0c43..835db332289 100644 --- a/Documentation/EDID/HOWTO.txt +++ b/Documentation/EDID/HOWTO.txt @@ -18,21 +18,40 @@ CONFIG_DRM_LOAD_EDID_FIRMWARE was introduced. It allows to provide an individually prepared or corrected EDID data set in the /lib/firmware directory from where it is loaded via the firmware interface. The code (see drivers/gpu/drm/drm_edid_load.c) contains built-in data sets for -commonly used screen resolutions (1024x768, 1280x1024, 1680x1050, -1920x1080) as binary blobs, but the kernel source tree does not contain -code to create these data. In order to elucidate the origin of the -built-in binary EDID blobs and to facilitate the creation of individual -data for a specific misbehaving monitor, commented sources and a -Makefile environment are given here. +commonly used screen resolutions (800x600, 1024x768, 1280x1024, 1600x1200, +1680x1050, 1920x1080) as binary blobs, but the kernel source tree does +not contain code to create these data. In order to elucidate the origin +of the built-in binary EDID blobs and to facilitate the creation of +individual data for a specific misbehaving monitor, commented sources +and a Makefile environment are given here. To create binary EDID and C source code files from the existing data material, simply type "make". -If you want to create your own EDID file, copy the file 1024x768.S and -replace the settings with your own data. The CRC value in the last line +If you want to create your own EDID file, copy the file 1024x768.S, +replace the settings with your own data and add a new target to the +Makefile. Please note that the EDID data structure expects the timing +values in a different way as compared to the standard X11 format. + +X11: +HTimings: hdisp hsyncstart hsyncend htotal +VTimings: vdisp vsyncstart vsyncend vtotal + +EDID: +#define XPIX hdisp +#define XBLANK htotal-hdisp +#define XOFFSET hsyncstart-hdisp +#define XPULSE hsyncend-hsyncstart + +#define YPIX vdisp +#define YBLANK vtotal-vdisp +#define YOFFSET (63+(vsyncstart-vdisp)) +#define YPULSE (63+(vsyncend-vsyncstart)) + +The CRC value in the last line #define CRC 0x55 -is a bit tricky. After a first version of the binary data set is -created, it must be be checked with the "edid-decode" utility which will +also is a bit tricky. After a first version of the binary data set is +created, it must be checked with the "edid-decode" utility which will most probably complain about a wrong CRC. Fortunately, the utility also displays the correct CRC which must then be inserted into the source file. After the make procedure is repeated, the EDID data set is ready |